Vancomycin is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. Vancomycin is the international nonproprietary name (INN) corresponding to the compound with the following formula:

It has been proposed that vancomycin acts by inhibiting proper cell wall synthesis in Gram-positive bacteria. More specifically, it is believed that vancomycin prevents incorporation of N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG)glycan subunits into the peptidoglycan matrix; which forms the major structural component of Gram-positive cell walls. The binding of vancomycin to the terminal D-alanyl-D-alanine moieties of the NAM/NAG-peptides prevents their incorporation into the peptidoglycan matrix.
Vancomycin has been administered intravenously for systemic therapy, as well as orally in the treatment of pseudomembranous colitis. Vancomycin has also been used off-label in a nebulized aerosol form for the treatment of various infections of the upper and lower respiratory tract. However, the use of an approved drug in an off-label manner may put a patient at risk as the safety and efficacy have not been studied and/or the appropriate dose may not be given. Furthermore, delivery by nebulization can take up to 20 minutes, which is a significant burden to patients. Currently, there are no known commercially available dry powder inhalable forms of vancomycin.